1. Field of the Invention
The present invention relates to a planar motor used for performing fine positional control of a stage of a microscope or the like.
2. Description of the Related Art
Hitherto, as a device adapted to position an object two-dimensionally in X-axis and Y-axis directions, an X-Y stage is widely known. The X-Y stage is constructed of a stage that includes ball screws and servo motors installed in a linear guide and extends in one direction, and another stage stacked in the direction orthogonal with respect to the above stage.
Another well-known planar motor has a X-axis drive linear motor and a Y-axis drive linear motor of variable reluctance type pulse motors that are disposed on the same plane, as disclosed in Japanese Unexamined Patent Application Publication No. H10-75562. Still another well-known planar motor has a biaxial linear motor and a plurality of laser interferometers used as position detectors for accomplishing highly accurate positioning in three directions of the plane, as disclosed in Japanese Patent Application No. H3-172326.
The first planar motor described above has the stack construction, making it difficult to reduce its thickness. Furthermore, the planar motor requires more mechanical components, which adversely affects responsiveness and accuracy due to lost motion from backlashes or stage weight.
The second planar motor is basically composed of pulse motors, so that it cannot be controlled in case of step-out. Furthermore, vibration during operation cannot be eliminated even if an ingenious control means is adopted.
The third planar motor requires an expensive peripheral device for positional detection and involves difficult alignment at installation.